vinylscratchp0n3 Posted August 6, 2015 Share Posted August 6, 2015 My dad wants to put a catless downpipe on his OBXT to remove the heat of the cat in the stock one. He doesn't believe me (and all the other posts on here and NASIOC) that you need a tune with a downpipe. Has anyone done a downpipe without a tune and not blown up an engine? A good explanation of what happens without a tune (running lean, boost creep, etc) would be great too, thanks! What I've suggested to him is the catless uppipe+downpipe and Perrin TMIC tuned build shown here: http://legacygt.com/forums/showthread.php/pdxtuning-legacy-tuning-wrapup-13536.html?t=13536 But he thinks that the only thing removing the cat will do is throw the P0420 code (and that putting a spark plug anti fouler on the rear O2 sensor will make it go away), and it won't make it run damagingly lean, even though he acknowledges that the stock tune is already very lean. He says he's taken honeycomb type cats off of Nissans and it didn't affect them negatively. He also wants to put the stock Legacy GT suspension on to lower it from Outback height. What parts do we need, and will it rub with the stock 17" Outback wheels, or do we need LGT wheels? Link to comment Share on other sites More sharing options...
kongzilla Posted August 6, 2015 Share Posted August 6, 2015 You will need a tune. You will be fine with stock wheels on lgt suspension. Link to comment Share on other sites More sharing options...
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